I have to say that personally I think a quick go over with the jet wash every month and a hoover out every so often is about all I can be bothered with. It get filthy this time of year within 5 minutes of driving, so it's pretty pointless to spend forever cleaning. Last time I used a drive through car wash it was crap. It didn't clean any detail or indentations in the bodywork. It's hard to explain, but it didn't clean in the bits that actually get the most dirty. Seemed a waste of time.